The colour codes are included in the catalogues, for ordering purposes.
1) photo from company catalogue of Angelfish M-236-17-62 (colour code 62)
2) Angelfish M-236-17 from my collection
3) photo of inscription on my Angelfish: Marcolin Sweden M236-17
FM Konstglas/Marcolin Ronneby, Sweden, do not include the colour code
in the signature on the base/bottom of the objects.